The overall objective of the proposed research is the characterization of the kinetics of growth and dissolution of renal stone-forming minerals such as magnesium ammonium phosphate, the calcium oxalate hydrates, uric acid, calcium phosphate and the urates. The highly reproducible procedure of seeded growth in stable supersaturated solutions under conditions of constant composition, developed in our laboratory, will be used and a range of ionic strength, concentration and pH typical of those in urines will be studied in order to provide information about the nature of the solid phases formed in the stone-forming process. Emphasis will be placed on the elucidation of the factors controlling the formation of the mixed mineral solid phases (e.g., by epitaxy) found in renal stones; the influence of individual urine components on this process will be investigated. In parallel with these studies, specific surface area, scanning electron microscopic and electron microprobe investigations of the growing crystals will be made in order to relate crystal morphology to the kinetics of the growth process. The influence of stone inhibitors and urinary components on the kinetics of transformation between the tri-, di-, and mono-hydrates of calcium oxalate and uric acid yields sodium urate will be investigated. Kinetic studies of the precipitation of stone-forming minerals upon representative stone materials will be made as a function of solution composition and in the presence of inhibitors.